# -*- coding: utf-8 -*-
"""Classes for managing templates and their runtime and compile time
options.
"""
import os
import sys
import weakref
from functools import partial
from functools import reduce

from markupsafe import Markup

from . import nodes
from ._compat import encode_filename
from ._compat import implements_iterator
from ._compat import implements_to_string
from ._compat import iteritems
from ._compat import PY2
from ._compat import PYPY
from ._compat import reraise
from ._compat import string_types
from ._compat import text_type
from .compiler import CodeGenerator
from .compiler import generate
from .defaults import BLOCK_END_STRING
from .defaults import BLOCK_START_STRING
from .defaults import COMMENT_END_STRING
from .defaults import COMMENT_START_STRING
from .defaults import DEFAULT_FILTERS
from .defaults import DEFAULT_NAMESPACE
from .defaults import DEFAULT_POLICIES
from .defaults import DEFAULT_TESTS
from .defaults import KEEP_TRAILING_NEWLINE
from .defaults import LINE_COMMENT_PREFIX
from .defaults import LINE_STATEMENT_PREFIX
from .defaults import LSTRIP_BLOCKS
from .defaults import NEWLINE_SEQUENCE
from .defaults import TRIM_BLOCKS
from .defaults import VARIABLE_END_STRING
from .defaults import VARIABLE_START_STRING
from .exceptions import TemplateNotFound
from .exceptions import TemplateRuntimeError
from .exceptions import TemplatesNotFound
from .exceptions import TemplateSyntaxError
from .exceptions import UndefinedError
from .lexer import get_lexer
from .lexer import TokenStream
from .nodes import EvalContext
from .parser import Parser
from .runtime import Context
from .runtime import new_context
from .runtime import Undefined
from .utils import concat
from .utils import consume
from .utils import have_async_gen
from .utils import import_string
from .utils import internalcode
from .utils import LRUCache
from .utils import missing

# for direct template usage we have up to ten living environments
_spontaneous_environments = LRUCache(10)


def get_spontaneous_environment(cls, *args):
 """Return a new spontaneous environment. A spontaneous environment
 is used for templates created directly rather than through an
 existing environment.

 :param cls: Environment class to create.
 :param args: Positional arguments passed to environment.
 """
 key = (cls, args)

 try:
 return _spontaneous_environments[key]
 except KeyError:
 _spontaneous_environments[key] = env = cls(*args)
 env.shared = True
 return env


def create_cache(size):
 """Return the cache class for the given size."""
 if size == 0:
 return None
 if size < 0:
 return {}
 return LRUCache(size)


def copy_cache(cache):
 """Create an empty copy of the given cache."""
 if cache is None:
 return None
 elif type(cache) is dict:
 return {}
 return LRUCache(cache.capacity)


def load_extensions(environment, extensions):
 """Load the extensions from the list and bind it to the environment.
 Returns a dict of instantiated environments.
 """
 result = {}
 for extension in extensions:
 if isinstance(extension, string_types):
 extension = import_string(extension)
 result[extension.identifier] = extension(environment)
 return result


def fail_for_missing_callable(string, name):
 msg = string % name
 if isinstance(name, Undefined):
 try:
 name._fail_with_undefined_error()
 except Exception as e:
 msg = "%s (%s; did you forget to quote the callable name?)" % (msg, e)
 raise TemplateRuntimeError(msg)


def _environment_sanity_check(environment):
 """Perform a sanity check on the environment."""
 assert issubclass(
 environment.undefined, Undefined
 ), "undefined must be a subclass of undefined because filters depend on it."
 assert (
 environment.block_start_string
 != environment.variable_start_string
 != environment.comment_start_string
 ), "block, variable and comment start strings must be different"
 assert environment.newline_sequence in (
 "\r",
 "\r\n",
 "\n",
 ), "newline_sequence set to unknown line ending string."
 return environment


class Environment(object):
 r"""The core component of Jinja is the `Environment`. It contains
 important shared variables like configuration, filters, tests,
 globals and others. Instances of this class may be modified if
 they are not shared and if no template was loaded so far.
 Modifications on environments after the first template was loaded
 will lead to surprising effects and undefined behavior.

 Here are the possible initialization parameters:

 `block_start_string`
 The string marking the beginning of a block. Defaults to ``'{%'``.

 `block_end_string`
 The string marking the end of a block. Defaults to ``'%}'``.

 `variable_start_string`
 The string marking the beginning of a print statement.
 Defaults to ``'{{'``.

 `variable_end_string`
 The string marking the end of a print statement. Defaults to
 ``'}}'``.

 `comment_start_string`
 The string marking the beginning of a comment. Defaults to ``'{#'``.

 `comment_end_string`
 The string marking the end of a comment. Defaults to ``'#}'``.

 `line_statement_prefix`
 If given and a string, this will be used as prefix for line based
 statements. See also :ref:`line-statements`.

 `line_comment_prefix`
 If given and a string, this will be used as prefix for line based
 comments. See also :ref:`line-statements`.

 .. versionadded:: 2.2

 `trim_blocks`
 If this is set to ``True`` the first newline after a block is
 removed (block, not variable tag!). Defaults to `False`.

 `lstrip_blocks`
 If this is set to ``True`` leading spaces and tabs are stripped
 from the start of a line to a block. Defaults to `False`.

 `newline_sequence`
 The sequence that starts a newline. Must be one of ``'\r'``,
 ``'\n'`` or ``'\r\n'``. The default is ``'\n'`` which is a
 useful default for Linux and OS X systems as well as web
 applications.

 `keep_trailing_newline`
 Preserve the trailing newline when rendering templates.
 The default is ``False``, which causes a single newline,
 if present, to be stripped from the end of the template.

 .. versionadded:: 2.7

 `extensions`
 List of Jinja extensions to use. This can either be import paths
 as strings or extension classes. For more information have a
 look at :ref:`the extensions documentation <jinja-extensions>`.

 `optimized`
 should the optimizer be enabled? Default is ``True``.

 `undefined`
 :class:`Undefined` or a subclass of it that is used to represent
 undefined values in the template.

 `finalize`
 A callable that can be used to process the result of a variable
 expression before it is output. For example one can convert
 ``None`` implicitly into an empty string here.

 `autoescape`
 If set to ``True`` the XML/HTML autoescaping feature is enabled by
 default. For more details about autoescaping see
 :class:`~markupsafe.Markup`. As of Jinja 2.4 this can also
 be a callable that is passed the template name and has to
 return ``True`` or ``False`` depending on autoescape should be
 enabled by default.

 .. versionchanged:: 2.4
 `autoescape` can now be a function

 `loader`
 The template loader for this environment.

 `cache_size`
 The size of the cache. Per default this is ``400`` which means
 that if more than 400 templates are loaded the loader will clean
 out the least recently used template. If the cache size is set to
 ``0`` templates are recompiled all the time, if the cache size is
 ``-1`` the cache will not be cleaned.

 .. versionchanged:: 2.8
 The cache size was increased to 400 from a low 50.

 `auto_reload`
 Some loaders load templates from locations where the template
 sources may change (ie: file system or database). If
 ``auto_reload`` is set to ``True`` (default) every time a template is
 requested the loader checks if the source changed and if yes, it
 will reload the template. For higher performance it's possible to
 disable that.

 `bytecode_cache`
 If set to a bytecode cache object, this object will provide a
 cache for the internal Jinja bytecode so that templates don't
 have to be parsed if they were not changed.

 See :ref:`bytecode-cache` for more information.

 `enable_async`
 If set to true this enables async template execution which allows
 you to take advantage of newer Python features. This requires
 Python 3.6 or later.
 """

 #: if this environment is sandboxed. Modifying this variable won't make
 #: the environment sandboxed though. For a real sandboxed environment
 #: have a look at jinja2.sandbox. This flag alone controls the code
 #: generation by the compiler.
 sandboxed = False

 #: True if the environment is just an overlay
 overlayed = False

 #: the environment this environment is linked to if it is an overlay
 linked_to = None

 #: shared environments have this set to `True`. A shared environment
 #: must not be modified
 shared = False

 #: the class that is used for code generation. See
 #: :class:`~jinja2.compiler.CodeGenerator` for more information.
 code_generator_class = CodeGenerator

 #: the context class thatis used for templates. See
 #: :class:`~jinja2.runtime.Context` for more information.
 context_class = Context

 def __init__(
 self,
 block_start_string=BLOCK_START_STRING,
 block_end_string=BLOCK_END_STRING,
 variable_start_string=VARIABLE_START_STRING,
 variable_end_string=VARIABLE_END_STRING,
 comment_start_string=COMMENT_START_STRING,
 comment_end_string=COMMENT_END_STRING,
 line_statement_prefix=LINE_STATEMENT_PREFIX,
 line_comment_prefix=LINE_COMMENT_PREFIX,
 trim_blocks=TRIM_BLOCKS,
 lstrip_blocks=LSTRIP_BLOCKS,
 newline_sequence=NEWLINE_SEQUENCE,
 keep_trailing_newline=KEEP_TRAILING_NEWLINE,
 extensions=(),
 optimized=True,
 undefined=Undefined,
 finalize=None,
 autoescape=False,
 loader=None,
 cache_size=400,
 auto_reload=True,
 bytecode_cache=None,
 enable_async=False,
 ):
 # !!Important notice!!
 # The constructor accepts quite a few arguments that should be
 # passed by keyword rather than position. However it's important to
 # not change the order of arguments because it's used at least
 # internally in those cases:
 # - spontaneous environments (i18n extension and Template)
 # - unittests
 # If parameter changes are required only add parameters at the end
 # and don't change the arguments (or the defaults!) of the arguments
 # existing already.

 # lexer / parser information
 self.block_start_string = block_start_string
 self.block_end_string = block_end_string
 self.variable_start_string = variable_start_string
 self.variable_end_string = variable_end_string
 self.comment_start_string = comment_start_string
 self.comment_end_string = comment_end_string
 self.line_statement_prefix = line_statement_prefix
 self.line_comment_prefix = line_comment_prefix
 self.trim_blocks = trim_blocks
 self.lstrip_blocks = lstrip_blocks
 self.newline_sequence = newline_sequence
 self.keep_trailing_newline = keep_trailing_newline

 # runtime information
 self.undefined = undefined
 self.optimized = optimized
 self.finalize = finalize
 self.autoescape = autoescape

 # defaults
 self.filters = DEFAULT_FILTERS.copy()
 self.tests = DEFAULT_TESTS.copy()
 self.globals = DEFAULT_NAMESPACE.copy()

 # set the loader provided
 self.loader = loader
 self.cache = create_cache(cache_size)
 self.bytecode_cache = bytecode_cache
 self.auto_reload = auto_reload

 # configurable policies
 self.policies = DEFAULT_POLICIES.copy()

 # load extensions
 self.extensions = load_extensions(self, extensions)

 self.enable_async = enable_async
 self.is_async = self.enable_async and have_async_gen
 if self.is_async:
 # runs patch_all() to enable async support
 from . import asyncsupport # noqa: F401

 _environment_sanity_check(self)

 def add_extension(self, extension):
 """Adds an extension after the environment was created.

 .. versionadded:: 2.5
 """
 self.extensions.update(load_extensions(self, [extension]))

 def extend(self, **attributes):
 """Add the items to the instance of the environment if they do not exist
 yet. This is used by :ref:`extensions <writing-extensions>` to register
 callbacks and configuration values without breaking inheritance.
 """
 for key, value in iteritems(attributes):
 if not hasattr(self, key):
 setattr(self, key, value)

 def overlay(
 self,
 block_start_string=missing,
 block_end_string=missing,
 variable_start_string=missing,
 variable_end_string=missing,
 comment_start_string=missing,
 comment_end_string=missing,
 line_statement_prefix=missing,
 line_comment_prefix=missing,
 trim_blocks=missing,
 lstrip_blocks=missing,
 extensions=missing,
 optimized=missing,
 undefined=missing,
 finalize=missing,
 autoescape=missing,
 loader=missing,
 cache_size=missing,
 auto_reload=missing,
 bytecode_cache=missing,
 ):
 """Create a new overlay environment that shares all the data with the
 current environment except for cache and the overridden attributes.
 Extensions cannot be removed for an overlayed environment. An overlayed
 environment automatically gets all the extensions of the environment it
 is linked to plus optional extra extensions.

 Creating overlays should happen after the initial environment was set
 up completely. Not all attributes are truly linked, some are just
 copied over so modifications on the original environment may not shine
 through.
 """
 args = dict(locals())
 del args["self"], args["cache_size"], args["extensions"]

 rv = object.__new__(self.__class__)
 rv.__dict__.update(self.__dict__)
 rv.overlayed = True
 rv.linked_to = self

 for key, value in iteritems(args):
 if value is not missing:
 setattr(rv, key, value)

 if cache_size is not missing:
 rv.cache = create_cache(cache_size)
 else:
 rv.cache = copy_cache(self.cache)

 rv.extensions = {}
 for key, value in iteritems(self.extensions):
 rv.extensions[key] = value.bind(rv)
 if extensions is not missing:
 rv.extensions.update(load_extensions(rv, extensions))

 return _environment_sanity_check(rv)

 lexer = property(get_lexer, doc="The lexer for this environment.")

 def iter_extensions(self):
 """Iterates over the extensions by priority."""
 return iter(sorted(self.extensions.values(), key=lambda x: x.priority))

 def getitem(self, obj, argument):
 """Get an item or attribute of an object but prefer the item."""
 try:
 return obj[argument]
 except (AttributeError, TypeError, LookupError):
 if isinstance(argument, string_types):
 try:
 attr = str(argument)
 except Exception:
 pass
 else:
 try:
 return getattr(obj, attr)
 except AttributeError:
 pass
 return self.undefined(obj=obj, name=argument)

 def getattr(self, obj, attribute):
 """Get an item or attribute of an object but prefer the attribute.
 Unlike :meth:`getitem` the attribute *must* be a bytestring.
 """
 try:
 return getattr(obj, attribute)
 except AttributeError:
 pass
 try:
 return obj[attribute]
 except (TypeError, LookupError, AttributeError):
 return self.undefined(obj=obj, name=attribute)

 def call_filter(
 self, name, value, args=None, kwargs=None, context=None, eval_ctx=None
 ):
 """Invokes a filter on a value the same way the compiler does it.

 Note that on Python 3 this might return a coroutine in case the
 filter is running from an environment in async mode and the filter
 supports async execution. It's your responsibility to await this
 if needed.

 .. versionadded:: 2.7
 """
 func = self.filters.get(name)
 if func is None:
 fail_for_missing_callable("no filter named %r", name)
 args = [value] + list(args or ())
 if getattr(func, "contextfilter", False) is True:
 if context is None:
 raise TemplateRuntimeError(
 "Attempted to invoke context filter without context"
 )
 args.insert(0, context)
 elif getattr(func, "evalcontextfilter", False) is True:
 if eval_ctx is None:
 if context is not None:
 eval_ctx = context.eval_ctx
 else:
 eval_ctx = EvalContext(self)
 args.insert(0, eval_ctx)
 elif getattr(func, "environmentfilter", False) is True:
 args.insert(0, self)
 return func(*args, **(kwargs or {}))

 def call_test(self, name, value, args=None, kwargs=None):
 """Invokes a test on a value the same way the compiler does it.

 .. versionadded:: 2.7
 """
 func = self.tests.get(name)
 if func is None:
 fail_for_missing_callable("no test named %r", name)
 return func(value, *(args or ()), **(kwargs or {}))

 @internalcode
 def parse(self, source, name=None, filename=None):
 """Parse the sourcecode and return the abstract syntax tree. This
 tree of nodes is used by the compiler to convert the template into
 executable source- or bytecode. This is useful for debugging or to
 extract information from templates.

 If you are :ref:`developing Jinja extensions <writing-extensions>`
 this gives you a good overview of the node tree generated.
 """
 try:
 return self._parse(source, name, filename)
 except TemplateSyntaxError:
 self.handle_exception(source=source)

 def _parse(self, source, name, filename):
 """Internal parsing function used by `parse` and `compile`."""
 return Parser(self, source, name, encode_filename(filename)).parse()

 def lex(self, source, name=None, filename=None):
 """Lex the given sourcecode and return a generator that yields
 tokens as tuples in the form ``(lineno, token_type, value)``.
 This can be useful for :ref:`extension development <writing-extensions>`
 and debugging templates.

 This does not perform preprocessing. If you want the preprocessing
 of the extensions to be applied you have to filter source through
 the :meth:`preprocess` method.
 """
 source = text_type(source)
 try:
 return self.lexer.tokeniter(source, name, filename)
 except TemplateSyntaxError:
 self.handle_exception(source=source)

 def preprocess(self, source, name=None, filename=None):
 """Preprocesses the source with all extensions. This is automatically
 called for all parsing and compiling methods but *not* for :meth:`lex`
 because there you usually only want the actual source tokenized.
 """
 return reduce(
 lambda s, e: e.preprocess(s, name, filename),
 self.iter_extensions(),
 text_type(source),
 )

 def _tokenize(self, source, name, filename=None, state=None):
 """Called by the parser to do the preprocessing and filtering
 for all the extensions. Returns a :class:`~jinja2.lexer.TokenStream`.
 """
 source = self.preprocess(source, name, filename)
 stream = self.lexer.tokenize(source, name, filename, state)
 for ext in self.iter_extensions():
 stream = ext.filter_stream(stream)
 if not isinstance(stream, TokenStream):
 stream = TokenStream(stream, name, filename)
 return stream

 def _generate(self, source, name, filename, defer_init=False):
 """Internal hook that can be overridden to hook a different generate
 method in.

 .. versionadded:: 2.5
 """
 return generate(
 source,
 self,
 name,
 filename,
 defer_init=defer_init,
 optimized=self.optimized,
 )

 def _compile(self, source, filename):
 """Internal hook that can be overridden to hook a different compile
 method in.

 .. versionadded:: 2.5
 """
 return compile(source, filename, "exec")

 @internalcode
 def compile(self, source, name=None, filename=None, raw=False, defer_init=False):
 """Compile a node or template source code. The `name` parameter is
 the load name of the template after it was joined using
 :meth:`join_path` if necessary, not the filename on the file system.
 the `filename` parameter is the estimated filename of the template on
 the file system. If the template came from a database or memory this
 can be omitted.

 The return value of this method is a python code object. If the `raw`
 parameter is `True` the return value will be a string with python
 code equivalent to the bytecode returned otherwise. This method is
 mainly used internally.

 `defer_init` is use internally to aid the module code generator. This
 causes the generated code to be able to import without the global
 environment variable to be set.

 .. versionadded:: 2.4
 `defer_init` parameter added.
 """
 source_hint = None
 try:
 if isinstance(source, string_types):
 source_hint = source
 source = self._parse(source, name, filename)
 source = self._generate(source, name, filename, defer_init=defer_init)
 if raw:
 return source
 if filename is None:
 filename = "<template>"
 else:
 filename = encode_filename(filename)
 return self._compile(source, filename)
 except TemplateSyntaxError:
 self.handle_exception(source=source_hint)

 def compile_expression(self, source, undefined_to_none=True):
 """A handy helper method that returns a callable that accepts keyword
 arguments that appear as variables in the expression. If called it
 returns the result of the expression.

 This is useful if applications want to use the same rules as Jinja
 in template "configuration files" or similar situations.

 Example usage:

 >>> env = Environment()
 >>> expr = env.compile_expression('foo == 42')
 >>> expr(foo=23)
 False
 >>> expr(foo=42)
 True

 Per default the return value is converted to `None` if the
 expression returns an undefined value. This can be changed
 by setting `undefined_to_none` to `False`.

 >>> env.compile_expression('var')() is None
 True
 >>> env.compile_expression('var', undefined_to_none=False)()
 Undefined

 .. versionadded:: 2.1
 """
 parser = Parser(self, source, state="variable")
 try:
 expr = parser.parse_expression()
 if not parser.stream.eos:
 raise TemplateSyntaxError(
 "chunk after expression", parser.stream.current.lineno, None, None
 )
 expr.set_environment(self)
 except TemplateSyntaxError:
 if sys.exc_info() is not None:
 self.handle_exception(source=source)

 body = [nodes.Assign(nodes.Name("result", "store"), expr, lineno=1)]
 template = self.from_string(nodes.Template(body, lineno=1))
 return TemplateExpression(template, undefined_to_none)

 def compile_templates(
 self,
 target,
 extensions=None,
 filter_func=None,
 zip="deflated",
 log_function=None,
 ignore_errors=True,
 py_compile=False,
 ):
 """Finds all the templates the loader can find, compiles them
 and stores them in `target`. If `zip` is `None`, instead of in a
 zipfile, the templates will be stored in a directory.
 By default a deflate zip algorithm is used. To switch to
 the stored algorithm, `zip` can be set to ``'stored'``.

 `extensions` and `filter_func` are passed to :meth:`list_templates`.
 Each template returned will be compiled to the target folder or
 zipfile.

 By default template compilation errors are ignored. In case a
 log function is provided, errors are logged. If you want template
 syntax errors to abort the compilation you can set `ignore_errors`
 to `False` and you will get an exception on syntax errors.

 If `py_compile` is set to `True` .pyc files will be written to the
 target instead of standard .py files. This flag does not do anything
 on pypy and Python 3 where pyc files are not picked up by itself and
 don't give much benefit.

 .. versionadded:: 2.4
 """
 from .loaders import ModuleLoader

 if log_function is None:

 def log_function(x):
 pass

 if py_compile:
 if not PY2 or PYPY:
 import warnings

 warnings.warn(
 "'py_compile=True' has no effect on PyPy or Python"
 " 3 and will be removed in version 3.0",
 DeprecationWarning,
 stacklevel=2,
 )
 py_compile = False
 else:
 import imp
 import marshal

 py_header = imp.get_magic() + u"\xff\xff\xff\xff".encode("iso-8859-15")

 # Python 3.3 added a source filesize to the header
 if sys.version_info >= (3, 3):
 py_header += u"\x00\x00\x00\x00".encode("iso-8859-15")

 def write_file(filename, data):
 if zip:
 info = ZipInfo(filename)
 info.external_attr = 0o755 << 16
 zip_file.writestr(info, data)
 else:
 if isinstance(data, text_type):
 data = data.encode("utf8")

 with open(os.path.join(target, filename), "wb") as f:
 f.write(data)

 if zip is not None:
 from zipfile import ZipFile, ZipInfo, ZIP_DEFLATED, ZIP_STORED

 zip_file = ZipFile(
 target, "w", dict(deflated=ZIP_DEFLATED, stored=ZIP_STORED)[zip]
 )
 log_function('Compiling into Zip archive "%s"' % target)
 else:
 if not os.path.isdir(target):
 os.makedirs(target)
 log_function('Compiling into folder "%s"' % target)

 try:
 for name in self.list_templates(extensions, filter_func):
 source, filename, _ = self.loader.get_source(self, name)
 try:
 code = self.compile(source, name, filename, True, True)
 except TemplateSyntaxError as e:
 if not ignore_errors:
 raise
 log_function('Could not compile "%s": %s' % (name, e))
 continue

 filename = ModuleLoader.get_module_filename(name)

 if py_compile:
 c = self._compile(code, encode_filename(filename))
 write_file(filename + "c", py_header + marshal.dumps(c))
 log_function('Byte-compiled "%s" as %s' % (name, filename + "c"))
 else:
 write_file(filename, code)
 log_function('Compiled "%s" as %s' % (name, filename))
 finally:
 if zip:
 zip_file.close()

 log_function("Finished compiling templates")

 def list_templates(self, extensions=None, filter_func=None):
 """Returns a list of templates for this environment. This requires
 that the loader supports the loader's
 :meth:`~BaseLoader.list_templates` method.

 If there are other files in the template folder besides the
 actual templates, the returned list can be filtered. There are two
 ways: either `extensions` is set to a list of file extensions for
 templates, or a `filter_func` can be provided which is a callable that
 is passed a template name and should return `True` if it should end up
 in the result list.

 If the loader does not support that, a :exc:`TypeError` is raised.

 .. versionadded:: 2.4
 """
 names = self.loader.list_templates()

 if extensions is not None:
 if filter_func is not None:
 raise TypeError(
 "either extensions or filter_func can be passed, but not both"
 )

 def filter_func(x):
 return "." in x and x.rsplit(".", 1)[1] in extensions

 if filter_func is not None:
 names = [name for name in names if filter_func(name)]

 return names

 def handle_exception(self, source=None):
 """Exception handling helper. This is used internally to either raise
 rewritten exceptions or return a rendered traceback for the template.
 """
 from .debug import rewrite_traceback_stack

 reraise(*rewrite_traceback_stack(source=source))

 def join_path(self, template, parent):
 """Join a template with the parent. By default all the lookups are
 relative to the loader root so this method returns the `template`
 parameter unchanged, but if the paths should be relative to the
 parent template, this function can be used to calculate the real
 template name.

 Subclasses may override this method and implement template path
 joining here.
 """
 return template

 @internalcode
 def _load_template(self, name, globals):
 if self.loader is None:
 raise TypeError("no loader for this environment specified")
 cache_key = (weakref.ref(self.loader), name)
 if self.cache is not None:
 template = self.cache.get(cache_key)
 if template is not None and (
 not self.auto_reload or template.is_up_to_date
 ):
 return template
 template = self.loader.load(self, name, globals)
 if self.cache is not None:
 self.cache[cache_key] = template
 return template

 @internalcode
 def get_template(self, name, parent=None, globals=None):
 """Load a template from the loader. If a loader is configured this
 method asks the loader for the template and returns a :class:`Template`.
 If the `parent` parameter is not `None`, :meth:`join_path` is called
 to get the real template name before loading.

 The `globals` parameter can be used to provide template wide globals.
 These variables are available in the context at render time.

 If the template does not exist a :exc:`TemplateNotFound` exception is
 raised.

 .. versionchanged:: 2.4
 If `name` is a :class:`Template` object it is returned from the
 function unchanged.
 """
 if isinstance(name, Template):
 return name
 if parent is not None:
 name = self.join_path(name, parent)
 return self._load_template(name, self.make_globals(globals))

 @internalcode
 def select_template(self, names, parent=None, globals=None):
 """Works like :meth:`get_template` but tries a number of templates
 before it fails. If it cannot find any of the templates, it will
 raise a :exc:`TemplatesNotFound` exception.

 .. versionchanged:: 2.11
 If names is :class:`Undefined`, an :exc:`UndefinedError` is
 raised instead. If no templates were found and names
 contains :class:`Undefined`, the message is more helpful.

 .. versionchanged:: 2.4
 If `names` contains a :class:`Template` object it is returned
 from the function unchanged.

 .. versionadded:: 2.3
 """
 if isinstance(names, Undefined):
 names._fail_with_undefined_error()

 if not names:
 raise TemplatesNotFound(
 message=u"Tried to select from an empty list " u"of templates."
 )
 globals = self.make_globals(globals)
 for name in names:
 if isinstance(name, Template):
 return name
 if parent is not None:
 name = self.join_path(name, parent)
 try:
 return self._load_template(name, globals)
 except (TemplateNotFound, UndefinedError):
 pass
 raise TemplatesNotFound(names)

 @internalcode
 def get_or_select_template(self, template_name_or_list, parent=None, globals=None):
 """Does a typecheck and dispatches to :meth:`select_template`
 if an iterable of template names is given, otherwise to
 :meth:`get_template`.

 .. versionadded:: 2.3
 """
 if isinstance(template_name_or_list, (string_types, Undefined)):
 return self.get_template(template_name_or_list, parent, globals)
 elif isinstance(template_name_or_list, Template):
 return template_name_or_list
 return self.select_template(template_name_or_list, parent, globals)

 def from_string(self, source, globals=None, template_class=None):
 """Load a template from a string. This parses the source given and
 returns a :class:`Template` object.
 """
 globals = self.make_globals(globals)
 cls = template_class or self.template_class
 return cls.from_code(self, self.compile(source), globals, None)

 def make_globals(self, d):
 """Return a dict for the globals."""
 if not d:
 return self.globals
 return dict(self.globals, **d)


class Template(object):
 """The central template object. This class represents a compiled template
 and is used to evaluate it.

 Normally the template object is generated from an :class:`Environment` but
 it also has a constructor that makes it possible to create a template
 instance directly using the constructor. It takes the same arguments as
 the environment constructor but it's not possible to specify a loader.

 Every template object has a few methods and members that are guaranteed
 to exist. However it's important that a template object should be
 considered immutable. Modifications on the object are not supported.

 Template objects created from the constructor rather than an environment
 do have an `environment` attribute that points to a temporary environment
 that is probably shared with other templates created with the constructor
 and compatible settings.

 >>> template = Template('Hello {{ name }}!')
 >>> template.render(name='John Doe') == u'Hello John Doe!'
 True
 >>> stream = template.stream(name='John Doe')
 >>> next(stream) == u'Hello John Doe!'
 True
 >>> next(stream)
 Traceback (most recent call last):
 ...
 StopIteration
 """

 #: Type of environment to create when creating a template directly
 #: rather than through an existing environment.
 environment_class = Environment

 def __new__(
 cls,
 source,
 block_start_string=BLOCK_START_STRING,
 block_end_string=BLOCK_END_STRING,
 variable_start_string=VARIABLE_START_STRING,
 variable_end_string=VARIABLE_END_STRING,
 comment_start_string=COMMENT_START_STRING,
 comment_end_string=COMMENT_END_STRING,
 line_statement_prefix=LINE_STATEMENT_PREFIX,
 line_comment_prefix=LINE_COMMENT_PREFIX,
 trim_blocks=TRIM_BLOCKS,
 lstrip_blocks=LSTRIP_BLOCKS,
 newline_sequence=NEWLINE_SEQUENCE,
 keep_trailing_newline=KEEP_TRAILING_NEWLINE,
 extensions=(),
 optimized=True,
 undefined=Undefined,
 finalize=None,
 autoescape=False,
 enable_async=False,
 ):
 env = get_spontaneous_environment(
 cls.environment_class,
 block_start_string,
 block_end_string,
 variable_start_string,
 variable_end_string,
 comment_start_string,
 comment_end_string,
 line_statement_prefix,
 line_comment_prefix,
 trim_blocks,
 lstrip_blocks,
 newline_sequence,
 keep_trailing_newline,
 frozenset(extensions),
 optimized,
 undefined,
 finalize,
 autoescape,
 None,
 0,
 False,
 None,
 enable_async,
 )
 return env.from_string(source, template_class=cls)

 @classmethod
 def from_code(cls, environment, code, globals, uptodate=None):
 """Creates a template object from compiled code and the globals. This
 is used by the loaders and environment to create a template object.
 """
 namespace = {"environment": environment, "__file__": code.co_filename}
 exec(code, namespace)
 rv = cls._from_namespace(environment, namespace, globals)
 rv._uptodate = uptodate
 return rv

 @classmethod
 def from_module_dict(cls, environment, module_dict, globals):
 """Creates a template object from a module. This is used by the
 module loader to create a template object.

 .. versionadded:: 2.4
 """
 return cls._from_namespace(environment, module_dict, globals)

 @classmethod
 def _from_namespace(cls, environment, namespace, globals):
 t = object.__new__(cls)
 t.environment = environment
 t.globals = globals
 t.name = namespace["name"]
 t.filename = namespace["__file__"]
 t.blocks = namespace["blocks"]

 # render function and module
 t.root_render_func = namespace["root"]
 t._module = None

 # debug and loader helpers
 t._debug_info = namespace["debug_info"]
 t._uptodate = None

 # store the reference
 namespace["environment"] = environment
 namespace["__jinja_template__"] = t

 return t

 def render(self, *args, **kwargs):
 """This method accepts the same arguments as the `dict` constructor:
 A dict, a dict subclass or some keyword arguments. If no arguments
 are given the context will be empty. These two calls do the same::

 template.render(knights='that say nih')
 template.render({'knights': 'that say nih'})

 This will return the rendered template as unicode string.
 """
 vars = dict(*args, **kwargs)
 try:
 return concat(self.root_render_func(self.new_context(vars)))
 except Exception:
 self.environment.handle_exception()

 def render_async(self, *args, **kwargs):
 """This works similar to :meth:`render` but returns a coroutine
 that when awaited returns the entire rendered template string. This
 requires the async feature to be enabled.

 Example usage::

 await template.render_async(knights='that say nih; asynchronously')
 """
 # see asyncsupport for the actual implementation
 raise NotImplementedError(
 "This feature is not available for this version of Python"
 )

 def stream(self, *args, **kwargs):
 """Works exactly like :meth:`generate` but returns a
 :class:`TemplateStream`.
 """
 return TemplateStream(self.generate(*args, **kwargs))

 def generate(self, *args, **kwargs):
 """For very large templates it can be useful to not render the whole
 template at once but evaluate each statement after another and yield
 piece for piece. This method basically does exactly that and returns
 a generator that yields one item after another as unicode strings.

 It accepts the same arguments as :meth:`render`.
 """
 vars = dict(*args, **kwargs)
 try:
 for event in self.root_render_func(self.new_context(vars)):
 yield event
 except Exception:
 yield self.environment.handle_exception()

 def generate_async(self, *args, **kwargs):
 """An async version of :meth:`generate`. Works very similarly but
 returns an async iterator instead.
 """
 # see asyncsupport for the actual implementation
 raise NotImplementedError(
 "This feature is not available for this version of Python"
 )

 def new_context(self, vars=None, shared=False, locals=None):
 """Create a new :class:`Context` for this template. The vars
 provided will be passed to the template. Per default the globals
 are added to the context. If shared is set to `True` the data
 is passed as is to the context without adding the globals.

 `locals` can be a dict of local variables for internal usage.
 """
 return new_context(
 self.environment, self.name, self.blocks, vars, shared, self.globals, locals
 )

 def make_module(self, vars=None, shared=False, locals=None):
 """This method works like the :attr:`module` attribute when called
 without arguments but it will evaluate the template on every call
 rather than caching it. It's also possible to provide
 a dict which is then used as context. The arguments are the same
 as for the :meth:`new_context` method.
 """
 return TemplateModule(self, self.new_context(vars, shared, locals))

 def make_module_async(self, vars=None, shared=False, locals=None):
 """As template module creation can invoke template code for
 asynchronous executions this method must be used instead of the
 normal :meth:`make_module` one. Likewise the module attribute
 becomes unavailable in async mode.
 """
 # see asyncsupport for the actual implementation
 raise NotImplementedError(
 "This feature is not available for this version of Python"
 )

 @internalcode
 def _get_default_module(self):
 if self._module is not None:
 return self._module
 self._module = rv = self.make_module()
 return rv

 @property
 def module(self):
 """The template as module. This is used for imports in the
 template runtime but is also useful if one wants to access
 exported template variables from the Python layer:

 >>> t = Template('{% macro foo() %}42{% endmacro %}23')
 >>> str(t.module)
 '23'
 >>> t.module.foo() == u'42'
 True

 This attribute is not available if async mode is enabled.
 """
 return self._get_default_module()

 def get_corresponding_lineno(self, lineno):
 """Return the source line number of a line number in the
 generated bytecode as they are not in sync.
 """
 for template_line, code_line in reversed(self.debug_info):
 if code_line <= lineno:
 return template_line
 return 1

 @property
 def is_up_to_date(self):
 """If this variable is `False` there is a newer version available."""
 if self._uptodate is None:
 return True
 return self._uptodate()

 @property
 def debug_info(self):
 """The debug info mapping."""
 if self._debug_info:
 return [tuple(map(int, x.split("="))) for x in self._debug_info.split("&")]
 return []

 def __repr__(self):
 if self.name is None:
 name = "memory:%x" % id(self)
 else:
 name = repr(self.name)
 return "<%s %s>" % (self.__class__.__name__, name)


@implements_to_string
class TemplateModule(object):
 """Represents an imported template. All the exported names of the
 template are available as attributes on this object. Additionally
 converting it into an unicode- or bytestrings renders the contents.
 """

 def __init__(self, template, context, body_stream=None):
 if body_stream is None:
 if context.environment.is_async:
 raise RuntimeError(
 "Async mode requires a body stream "
 "to be passed to a template module. Use "
 "the async methods of the API you are "
 "using."
 )
 body_stream = list(template.root_render_func(context))
 self._body_stream = body_stream
 self.__dict__.update(context.get_exported())
 self.__name__ = template.name

 def __html__(self):
 return Markup(concat(self._body_stream))

 def __str__(self):
 return concat(self._body_stream)

 def __repr__(self):
 if self.__name__ is None:
 name = "memory:%x" % id(self)
 else:
 name = repr(self.__name__)
 return "<%s %s>" % (self.__class__.__name__, name)


class TemplateExpression(object):
 """The :meth:`jinja2.Environment.compile_expression` method returns an
 instance of this object. It encapsulates the expression-like access
 to the template with an expression it wraps.
 """

 def __init__(self, template, undefined_to_none):
 self._template = template
 self._undefined_to_none = undefined_to_none

 def __call__(self, *args, **kwargs):
 context = self._template.new_context(dict(*args, **kwargs))
 consume(self._template.root_render_func(context))
 rv = context.vars["result"]
 if self._undefined_to_none and isinstance(rv, Undefined):
 rv = None
 return rv


@implements_iterator
class TemplateStream(object):
 """A template stream works pretty much like an ordinary python generator
 but it can buffer multiple items to reduce the number of total iterations.
 Per default the output is unbuffered which means that for every unbuffered
 instruction in the template one unicode string is yielded.

 If buffering is enabled with a buffer size of 5, five items are combined
 into a new unicode string. This is mainly useful if you are streaming
 big templates to a client via WSGI which flushes after each iteration.
 """

 def __init__(self, gen):
 self._gen = gen
 self.disable_buffering()

 def dump(self, fp, encoding=None, errors="strict"):
 """Dump the complete stream into a file or file-like object.
 Per default unicode strings are written, if you want to encode
 before writing specify an `encoding`.

 Example usage::

 Template('Hello {{ name }}!').stream(name='foo').dump('hello.html')
 """
 close = False
 if isinstance(fp, string_types):
 if encoding is None:
 encoding = "utf-8"
 fp = open(fp, "wb")
 close = True
 try:
 if encoding is not None:
 iterable = (x.encode(encoding, errors) for x in self)
 else:
 iterable = self
 if hasattr(fp, "writelines"):
 fp.writelines(iterable)
 else:
 for item in iterable:
 fp.write(item)
 finally:
 if close:
 fp.close()

 def disable_buffering(self):
 """Disable the output buffering."""
 self._next = partial(next, self._gen)
 self.buffered = False

 def _buffered_generator(self, size):
 buf = []
 c_size = 0
 push = buf.append

 while 1:
 try:
 while c_size < size:
 c = next(self._gen)
 push(c)
 if c:
 c_size += 1
 except StopIteration:
 if not c_size:
 return
 yield concat(buf)
 del buf[:]
 c_size = 0

 def enable_buffering(self, size=5):
 """Enable buffering. Buffer `size` items before yielding them."""
 if size <= 1:
 raise ValueError("buffer size too small")

 self.buffered = True
 self._next = partial(next, self._buffered_generator(size))

 def __iter__(self):
 return self

 def __next__(self):
 return self._next()


# hook in default template class. if anyone reads this comment: ignore that
# it's possible to use custom templates ;-)
Environment.template_class = Template